Chip-On-board (COB) technology involves mounting (integrating) an Application Specific Integrated Circuit (ASIC), processor, memory semiconductor die, or other die/chip directly on a substrate (typically the printed circuit board) without the need for a packaged component. In addition to the die bonding, the process of integrating the die/chip may include the wire bonding, and possibly testing before or after encapsulation.
As will be appreciated by those skilled in the art, COB technology can help achieve high integration density. For example, eliminating the Thin Small-Outline Package (TSOP) or Fine-Pitch Ball Grid Array (FBGA) component package reduces the required substrate area and assembly weight. The saving in area can be as much as 20% in some cases. Using conventional Printed Circuit Boards (PCBs) and standard wire bonding technology, COB technology can yield very substantial weight and volume reduction. COB technology also reduces the number of interconnects between an active die and the substrate (i.e., the package pins), which improves the overall circuit speed, leads to higher clock rates, better electrical performance and improved signal quality, and increases the overall reliability of the module. Also, unlike other types of packaging, COB packaging is a Chip Scalable Packaging (CSP), meaning the packaging is not as limited by dimensioning and size standards as, for example, TSOP packaging. Additional benefits of COB packaging include better protection against reverse-engineering and, in some instances, elimination of soldering associated with conventional packaging.
Those skilled in the art will appreciate that, in connection with various COB processes, a coating of an epoxy encapsulent (or glob top) is applied for hermetically sealing and protecting the die and the wire bonded interconnections. The glob top also acts like a heat spreader between dies, improves heat emission, adds low Coefficients of Thermal Expansion (CTEs), and provides a hermetically sealed module assembly. The die may be glued directly to the PCB, and therefore increased heat dissipation from the die through the PCB is provided for.
Because COB technology is less pervasive in semiconductor manufacturing as compared to other conventional technologies, there exist gaps in research and development efforts with respect to systems that derive benefit from COB technology. Accordingly, there is a need for improved systems that are characterized by COB technology.